Processing state information

ABSTRACT

A method of processing state information relating to user equipment in a communications system comprising a radio access network, the method comprising: maintaining current state information relating to the user equipment; and on the basis of a change of connection of the user equipment from a first cell to a second cell: transmitting a current value associated with a given state information part to the target radio access node in response to detecting at least one of one or more predetermined triggers that indicate that the target radio access node may not have received the current value from the source radio access node; or relying on the target radio access node having received the current value from the source radio access node if said at least one of said one or more predetermined triggers is not detected.

TECHNICAL FIELD

The present invention relates to processing state information.

BACKGROUND ART

Up to, and including, Release 10 (REL-10) of the Long Term Evolution(LTE) 3rd Generation Partnership Project (3GPP) specification number TS36.300 “Evolved Universal Terrestrial Radio Access (E-UTRA) and EvolvedUniversal Terrestrial Radio Access Network (E-UTRAN); OverallDescription; Stage 2”, User Equipment (UE) reporting related to featuressuch as Radio Link Failure (RLF) information availability, loggedmeasurement information availability and proximity indication. It isexpected that additional reporting will be introduced, for exampleregarding Multimedia Broadcast Multicast Services (MBMS) interest andin-device interference, in later releases.

The UE repeats reporting of such information following every cell changein connected mode, in other words following every handover or connectionre-establishment. Some such information, such as RLF information andlogged measurement information, is contained in mobility-relatedmessages. Other information is (expected to be) transferred by means ofa separate, dedicated message. It is expected that the UE will need toprovide the E-UTRAN with more and more up-to-date information. It isexpected that reporting on the part of the UE will increase,particularly following a change in cell.

DISCLOSURE OF INVENTION Technical Problem

It would be desirable to provide improvements in processing informationrelating to user equipment.

Solution to Problem

According to a first aspect of the invention, there is provided a methodof processing state information relating to user equipment in acommunications system comprising a radio access network, thecommunications system comprising:

a source radio access node that is associated with one or more cells;and

a target radio access node that is associated with one or more cells andthat is capable of receiving the state information from the source radioaccess node,

the method comprising:

maintaining current state information relating to the user equipment,the state information comprising at least one state information partassociated with one or more features for which state informationreporting may be configured in a cell, the at least one stateinformation part being associable with a plurality of different values;and

on the basis of a change of connection of the user equipment from afirst cell to a second cell:

transmitting a current value associated with a given state informationpart to the target radio access node in response to detecting at leastone of one or more predetermined triggers that indicate that the targetradio access node may not have received the current value from thesource radio access node; or

relying on the target radio access node having received the currentvalue from the source radio access node if said at least one of said oneor more predetermined triggers is not detected.

As such, unnecessary reporting of state information may be reduced. Saidrelying preferably comprises not transmitting a current value associatedwith a given state information part to the target radio access node ifsaid at least one of said one or more predetermined triggers is notdetected.

In some embodiments, the one or more predetermined triggers includedetermining that the target radio access node has not received thecurrent value from the source radio access node.

In some embodiments, the one or more predetermined triggers includedetermining that the current value has not been reported to the radioaccess network.

In some embodiments, the one or more predetermined triggers includedetermining that the current value may have been reported to the sourceradio access node too late for the source radio access node to havetransmitted it to the target radio access node.

In some embodiments, the at least one trigger includes determining thatthe current value was reported to the source radio access node within atleast one predetermined time period prior to receiving a messagerelating to the change in connection.

In some embodiments, the at least one predetermined time period includesa time period associated with a handover command.

In some embodiments, the message comprises a handover command.

In some embodiments, the at least one trigger includes determining thatthe current value was reported to the source radio access node within atleast one predetermined time period prior to detecting a failure in aconnection to the source radio access node.

In some embodiments, the at least one predetermined time period includesa time period associated with a re-establishment procedure.

In some embodiments, the at least one predetermined time period includesa time period specified in a telecommunications standard.

In some embodiments, the at least one predetermined time period includesa time period configured by the radio access network.

In some embodiments, the one or more predetermined triggers includereceiving, from the target radio access node, a message comprising atleast one predetermined indicator from which it can be determinedwhether or not the target radio access node has received the currentvalue from the source radio access node.

In some embodiments, the at least one predetermined indicator comprisesa version identifier indicating a version of the given state informationpart.

In some embodiments, the one or more predetermined triggers includedetermining that the version identifier received from the target radioaccess node does not correspond with a current version of the givenstate information part.

Some embodiments comprise:

including a version identifier indicating a version of the given stateinformation part when reporting the value associated with the givenstate information part to the radio access network.

Some embodiments comprise:

including a version identifier indicating a version of the given stateinformation part when reporting a change in the value associated withthe given state information part to the radio access network.

Some embodiments comprise:

advancing the version identifier indicating the version of the givenstate information part upon transmitting the change in the valueassociated with the given state information part to the radio accessnetwork.

In some embodiments, the version identifier is a common versionidentifier that indicates a version of both the given state informationpart and at least one additional state information part.

Some embodiments comprise:

including the common version identifier when reporting the valueassociated with the given state information part and/or the at least oneadditional state information part to the radio access network.

Some embodiments comprise:

including the common version identifier when reporting a change in thevalue associated with the given state information part and/or the atleast one additional state information part to the radio access network.

Some embodiments comprise:

advancing the common version identifier upon transmitting a change inthe value associated with the given state information part and/or the atleast one additional state information part to the radio access network.

In some embodiments, the one or more predetermined triggers include:

determining that the common version identifier received from the targetradio access node does not correspond with a current common version ofthe given state information part and the at least one additional stateinformation part; and

determining that the value currently associated with the given stateinformation part is different from the value associated with a versionof the given state information part as indicated by the received commonversion identifier.

In some embodiments, the message received from the target radio accessnode relates to handover.

In some embodiments, the message received from the target radio accessnode relates to a connection re-establishment procedure.

In some embodiments, the given state information part is associable witha version identifier that indicates a version of the given stateinformation part and the at least one predetermined indicator includes apredetermined version identifier value.

In some embodiments, the given state information part is associable witha version identifier that indicates a version of the given stateinformation part and the at least one predetermined indicator includesthe absence of a version identifier associated with the given stateinformation part.

In some embodiments, the at least one trigger includes determining thatthe source radio access node, and/or or one more radio access nodes towhich the user equipment was previously connected since the valuecurrently associated with the given state information part was reportedto the radio access network, does not support forwarding of stateinformation relating to the user equipment.

Some embodiments comprise:

transmitting the value currently associated with the given stateinformation part to the target radio access node in response to saiddetecting at least one predetermined trigger only if the given stateinformation part is associated with one or more features for which stateinformation reporting is configured in the second cell.

In some embodiments, the given state information part is associated withone or more features for which state information reporting is configuredin both the first cell and the second cell.

In some embodiments, the given state information part is associated withone or more features for which state information reporting is configuredin the second cell and for which state information reporting is notconfigured in the first cell.

In some embodiments, the at least one trigger includes determining thatthe given state information part is associated with one or more featuresfor which state information reporting is configured in the second celland for which state information reporting is not configured in the firstcell.

Some embodiments comprise:

transmitting an additional current value associated with a further givenstate information part to the target radio access node in response todetecting at least one of one or more predetermined triggers thatindicate that the target radio access node may not have received theadditional current value from the source radio access node; and

relying on the target radio access node having received the additionalcurrent value from the source radio access node if said at least one ofsaid one or more predetermined triggers is not detected.

In some embodiments, at least the current value and the additionalcurrent value are included in a single message to the target radioaccess node.

In some embodiments, the radio access network is an Evolved UniversalTerrestrial

Radio Access Network.

In some embodiments, one or both of the source radio access node and thetarget radio access node is an evolved Node B.

In some embodiments, the source radio access node operates a first radioaccess technology and the target radio access node operates a second,different radio access technology.

According to a second aspect of the invention, there is provided amethod of processing state information relating to user equipment in acommunications system comprising a radio access network, thecommunications system comprising:

a target radio access node that is associated with one or more cells andthat is capable of receiving state information from a source radioaccess node that is associated with one or more cells; and

user equipment that is configured to maintain current state informationrelating to the user equipment, the state information comprising atleast one state information part associated with one or more featuresfor which state information reporting may be configured in a cell, theat least one state information part being associable with a plurality ofdifferent values,

the method comprising, at the source radio access node:

receiving state information relating to the user device; and

transmitting at least part of the received state information to thetarget radio access node,

whereby, on the basis of a change of connection of the user equipmentfrom a first cell to a second cell:

the user equipment transmits a current value associated with a givenstate information part to the target radio access node in response todetecting at least one of one or more predetermined triggers thatindicate that the target radio access node may not have received thecurrent value from the source radio access node; or

the user equipment relies on the target radio access node havingreceived the current value from the source radio access node if said atleast one of said one or more predetermined triggers is not detected.

As such, unnecessary reporting of state information may be reduced.

Some embodiments comprise:

transmitting the at least part of the received state information in amessage associated with the change in connection from the source radioaccess node to the target radio access node.

In some embodiments, the message comprises a handover preparationmessage.

Some embodiments comprise:

including the at least part of the received state information in anAccess Stratum (AS)-context field in the handover preparation message.

Some embodiments comprise:

including the at least part of the received state information in aninformation container, the information container being a variable sizestring.

Some embodiments comprise:

receiving state information reports from the user equipment, the stateinformation reports identifying changes to the state informationrelating to the user equipment.

Some embodiments comprise:

receiving a version identifier indicating a version of at least part ofthe state information when the user equipment reports a value associatedwith the at least part of the state information.

Some embodiments comprise:

receiving a version identifier indicating a version of at least part ofthe state information when the user equipment reports a change in thevalue associated with the at least part of the state information.

Some embodiments comprise:

receiving at least some of the received state information from a radioaccess node to which the user equipment was previously connected.

In some embodiments, at least a part of the received state informationis not comprehensible by the source radio access node.

According to a third aspect of the invention, there is provided a methodof processing state information relating to user equipment in acommunications system comprising a radio access network, thecommunications system comprising:

a source radio access node that is associated with one or more cells;and

user equipment that is configured to maintain current state informationrelating to the user equipment, the state information comprising atleast one state information part associated with one or more featuresfor which state information reporting may be configured in a cell, theat least one state information part being associable with a plurality ofdifferent values,

the method comprising, at a target radio access node that is associatedwith one or more cells and that is capable of receiving the stateinformation from the source radio access node, on the basis of a changeof connection of the user equipment from a first cell to a second cell:

receiving a current value associated with a given state information partfrom the user equipment in response to the user equipment detecting atleast one of one or more predetermined triggers that indicate that thecurrent value from the source radio access node may not have beenreceived at the target radio access node; or

relying on having received the current value from the source radioaccess node if said at least one of said one or more predeterminedtriggers is not detected.

As such, unnecessary reporting of state information may be reduced.

Some embodiments comprise:

transmitting a message comprising at least one predetermined indicatorfrom which it can be determined whether or not the target radio accessnode has received the current value from the source radio access node.

In some embodiments, the at least one predetermined indicator comprisesa version identifier indicating a version of the given state informationpart.

Some embodiments comprise:

receiving at least the version identifier from the source radio accessnode.

In some embodiments, the version identifier is a common versionidentifier that indicates a version of both the given state informationpart and at least one additional state information part.

In some embodiments, the message received relates to handover.

In some embodiments, the message received relates to a connectionre-establishment procedure.

In some embodiments, the given state information part is associable witha version identifier that indicates a version of the given stateinformation part and wherein the at least one predetermined indicatorincludes a predetermined version identifier.

In some embodiments, the given state information part is associable witha version identifier that indicates a version of the given stateinformation part and wherein the at least one predetermined indicatorincludes the absence of a version identifier associated with the givenstate information part.

Some embodiments comprise:

receiving at least some of the state information relating to the userequipment in a message associated with the change in connection from thesource radio access node.

In some embodiments, the message comprises a handover preparationmessage.

According to a fourth aspect of the invention, there is providedapparatus for processing state information relating to user equipment ina communications system comprising a radio access network, thecommunications system comprising:

a source radio access node that is associated with one or more cells;and

a target radio access node that is associated with one or more cells andthat is capable of receiving the state information from the source radioaccess node, the apparatus being configured to:

maintain current state information relating to the user equipment, thestate information comprising at least one state information partassociated with one or more features for which state informationreporting may be configured in a cell, the at least one stateinformation part being associable with a plurality of different values;and

on the basis of a change of connection of the user equipment from afirst cell to a second cell:

transmit a current value associated with a given state information partto the target radio access node in response to detecting at least one ofone or more predetermined triggers that indicate that the target radioaccess node may not have received the current value from the sourceradio access node; or

rely on the target radio access node having received the current valuefrom the source radio access node if said at least one of said one ormore predetermined triggers is not detected.

According to a fifth aspect of the invention, there is providedapparatus for processing state information relating to user equipment ina communications system comprising a radio access network, thecommunications system comprising:

a target radio access node that is associated with one or more cells andthat is capable of receiving state information from a source radioaccess node that is associated with one or more cells; and

user equipment that is configured to maintain current state informationrelating to the user equipment, the state information comprising atleast one state information part associated with one or more featuresfor which state information reporting may be configured in a cell, theat least one state information part being associable with a plurality ofdifferent values, the apparatus being configured to:

receive state information relating to the user device; and

transmit at least part of the received state information to the targetradio access node,

whereby, on the basis of a change of connection of the user equipmentfrom a first cell to a second cell:

the user equipment transmits a current value associated with a givenstate information part to the target radio access node in response todetecting at least one of one or more predetermined triggers thatindicate that the target radio access node may not have received thecurrent value from the apparatus; or

the user equipment relies on the target radio access node havingreceived the current value from the apparatus if said at least one ofsaid one or more predetermined triggers is not detected.

According to a sixth aspect of the invention, there is providedapparatus for processing state information relating to user equipment ina communications system comprising a radio access network, thecommunications system comprising:

a source radio access node that is associated with one or more cells;and

user equipment that is configured to maintain current state informationrelating to the user equipment, the state information comprising atleast one state information part associated with one or more featuresfor which state information reporting may be configured in a cell, theat least one state information part being associable with a plurality ofdifferent values,

the apparatus being associated with one or more cells, being capable ofreceiving the state information from the source radio access node, andbeing configured to, on the basis of a change of connection of the userequipment from a first cell to a second cell:

receive a current value associated with a given state information partfrom the user equipment in response to the user equipment detecting atleast one of one or more pre-determined triggers that indicate that thecurrent value from the source radio access node may not have beenreceived at the target radio access node; or

rely on having received the current value from the source radio accessnode if said at least one of said one or more predetermined triggers isnot detected.

According to a seventh aspect of the invention, there is provided acomputer program product comprising a non-transitory computer-readablestorage medium having computer readable instructions stored thereon, thecomputer readable instructions being executable by a computerized deviceto cause the computerized device to perform a method of processing stateinformation relating to user equipment in a communications systemcomprising a radio access network, the communications system comprising:

a source radio access node that is associated with one or more cells;and

a target radio access node that is associated with one or more cells andthat is capable of receiving the state information from the source radioaccess node, the method comprising:

maintaining current state information relating to the user equipment,the state information comprising at least one state information partassociated with one or more features for which state informationreporting may be configured in a cell, the at least one stateinformation part being associable with a plurality of different values;and

on the basis of a change of connection of the user equipment from afirst cell to a second cell:

transmitting a current value associated with a given state informationpart to the target radio access node in response to detecting at leastone of one or more predetermined triggers that indicate that the targetradio access node may not have received the current value from thesource radio access node; or

relying on the target radio access node having received the currentvalue from the source radio access node if said at least one of said oneor more predetermined triggers is not detected.

According to an eighth aspect of the invention, there is providedcomputer program product comprising a non-transitory computer-readablestorage medium having computer readable instructions stored thereon, thecomputer readable instructions being executable by a computerized deviceto cause the computerized device to perform a method of processing stateinformation relating to user equipment in a communications systemcomprising a radio access network, the communications system comprising:

a target radio access node that is associated with one or more cells andthat is capable of receiving state information from a source radioaccess node that is associated with one or more cells; and

user equipment that is configured to maintain current state informationrelating to the user equipment, the state information comprising atleast one state information part associated with one or more featuresfor which state information reporting may be configured in a cell, theat least one state information part being associable with a plurality ofdifferent values,

the method comprising, at the source radio access node:

receiving state information relating to the user device; and

transmitting at least part of the received state information to thetarget radio access node,

whereby, on the basis of a change of connection of the user equipmentfrom a first cell to a second cell:

the user equipment transmits a current value associated with a givenstate information part to the target radio access node in response todetecting at least one of one or more predetermined triggers thatindicate that the target radio access node may not have received thecurrent value from the source radio access node, or

the user equipment relies on the target radio access node havingreceived the current value from the source radio access node if said atleast one of said one or more predetermined triggers is not detected.

According to a ninth aspect of the invention, there is provided acomputer program product comprising a non-transitory computer-readablestorage medium having computer readable instructions stored thereon, thecomputer readable instructions being executable by a computerized deviceto cause the computerized device to perform a method of processing stateinformation relating to user equipment in a communications systemcomprising a radio access network, the communications system comprising:

source radio access node that is associated with one or more cells; and

user equipment that is configured to maintain current state informationrelating to the user equipment, the state information comprising atleast one state information part associated with one or more featuresfor which state information reporting may be configured in a cell, theat least one state information part being associable with a plurality ofdifferent values,

the method comprising, at a target radio access node that is associatedwith one or more cells and that is capable of receiving the stateinformation from the source radio access node, on the basis of a changeof connection of the user equipment from a first cell to a second cell:

receiving a current value associated with a given state information partfrom the user equipment in response to the user equipment detecting atleast one of one or more pre-determined triggers that indicate that thecurrent value from the source radio access node may not have beenreceived at the target radio access node; or

relying on having received the current value from the source radioaccess node if said at least one of said one or more predeterminedtriggers is not detected.

Advantageous Effects of Invention

Processing State information of the present disclosure is capable ofreducing unnecessary reporting of state information.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block schematic representation of a communications systemaccording to some embodiments;

FIG. 2 shows a method of processing state information relating to userequipment according to some embodiments;

FIG. 3 shows a method of processing state information relating to userequipment according to some embodiments;

FIG. 4 shows a method of processing state information relating to userequipment according to some embodiments;

FIG. 5 shows a method of processing state information relating to userequipment according to some embodiments; and

FIG. 6 is a block schematic representation of a communications systemaccording to some embodiments.

MODE FOR THE INVENTION

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.Definitions for certain words and phrases are provided throughout thispatent document, those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases.

FIGS. 1 through 6, discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

The same reference numbers are used throughout the drawings to refer tothe same or like parts. In the drawings, certain elements may beexaggerated or omitted or schematically depicted for clarity of thedisclosure, and the actual sizes of the elements are not reflected.Exemplary embodiments of the present disclosure are described withreference to the accompanying drawings in detail.

FIG. 1 is a block schematic representation of a communications system100 according to some embodiments.

The communications system 100 includes a radio access network, generallyindicated in a dotted box in FIG. 1 and designated by reference 101. Insome embodiments, the radio access network 101 comprises an E-UTRAN. Atleast some embodiments are intended to be applicable to release 11(REL-11) and beyond of the E-UTRA. However, at least some embodimentsmay be applicable to other releases of the E-UTRA and/or other (radioaccess) systems.

The communications system 100 includes User Equipment (UE) 102. In someembodiments, the UE 102 is a mobile telephony device. However, othertypes of UE 102 are envisaged.

The radio access network 101 includes first and second radio accessnodes 103, 104. The first and second radio access nodes 103, 104 controlat least respective first and second cells 105, 106. It will beappreciated that one or both of the first and second radio access nodes103, 104 may control more than one cell. The first and second radioaccess nodes 103, 104 may be communicatively coupled by means of one ormore interfaces 107, 108, 109.

In some embodiments, the radio access nodes 103, 104 are evolved Node Bs(eNodeBs or eNBs). In such embodiments, the radio access nodes 103, 104may be able to interact directly with each other via an X2 interface 107and/or indirectly via respective Si interfaces 108, 109 to a CoreNetwork (CN) 110. In some embodiments, the first radio access node 103operates a first Radio Access Technology (RAT) and the second radioaccess node 104 operates a second, different RAT.

The UE 102 communicates with the first radio access node 103 via a firstradio link 111 and communicates with the second radio access node 104via a second radio link 112.

It will be appreciated that the communications system 100 may includemore than one UE 102 and the radio access network 101 may include morethan two radio access nodes and associated cells.

In some embodiments, one of the first and second radio access nodes, inthis case the first radio access node 103, is a source radio access node103 that is associated with a first cell 105. The source radio accessnode 103 may be configured to transmit state information relating to theUE 102. The other of the first and second radio access nodes, in thiscase the second radio access node 104, is a target radio access node 104that is associated with a second cell 106. The target radio access node104 is capable of receiving the state information from the source radioaccess node 103. The source radio access node 103 is configured totransmit the state information to the target radio access node 104 viathe at least one interface 107, 108, 109 between the source radio accessnode 103 and the target radio access node 104.

The UE 102 is configured to maintain current state information relatingto the UE 102. The state information comprises at least one stateinformation part that is associated with one or more features for whichstate information reporting may be configured in the first cell 105and/or the second cell 106. The at least one state information part isassociable with a plurality of different values. The state informationmay be at least partly dynamic.

In some embodiments, the state information comprises status informationrelating to the UE 102, for example relating to proximity to a ClosedSubscriber Group (CSG) cell, interest in MBMS services or in-deviceinterference. In some embodiments, the state information comprises UEcapability information, i.e. capability information relating to the UE102, which is dynamic and may change, for example support for RLFinformation availability and/or logged measurement informationavailability, UE category information, or power class (which may changefor example with the device is plugged into an external power source).One or more elements of the UE capability information may reflect thedata rate that the UE currently supports. The current state of thisinformation may depend on a task the UE 102 is performing e.g. playing agame, doing navigation, etc. In such cases the UE capabilities maychange, dependent on the current operational state of the UE 102.

Other types of state information that the UE 102 may report to the radioaccess network 101 are contemplated.

In some cases, the connection may change from the first cell 105 to thesecond cell 106. The connection may change, for example, as a result ofa handover or as a result of re-establishment following a connectionfailure. The UE 102 may detect such a connection change, for example byreceiving a handover command or by detecting the connection failure. Inembodiments in which the source radio access node 103 operates a firstRAT and the target radio access node 104 operates a second, differentRAT, this change in connection may be referred to as an inter-RAT cellchange.

In some embodiments, the source radio access node 103 receives stateinformation relating to the UE 102 and transmits the received stateinformation to the target radio access node 104.

In some embodiments, the source radio access node 103 is configured totransmit at least part of the state information in a message associatedwith the change in connection. Thus, in some embodiments, as part of thechange in connection (for example as part of handover preparation), thesource radio access node 103 provides the state information to thetarget radio access node 104. In some embodiments, the messageassociated with the change in connection comprises a handoverpreparation message. In some embodiments, the source radio access node103 is configured to include the at least part of the received stateinformation in an Access Stratum (AS)-context field in a handoverpreparation message. Thus, in some embodiments, the at least part of thestate information may be included in the AS-context field in aHandoverPreparationInformation message. In some embodiments, the sourceradio access node 103 is configured to include the at least part of thestate information in an information container, the information containerbeing a variable size string.

In some embodiments, the source radio access node 103 receives stateinformation reports from the UE 102. The state information reportsidentify changes to the state information relating to the UE 102. Insome embodiments, the UE 102 transmits state information reports only inthe event of a change to at least part of the state information.

Some embodiments comprise receiving at least some of the stateinformation from a radio access node (not shown in FIG. 1; see FIGS. 3to 5) to which the UE 102 was previously connected.

In some cases, the state information received from the previous radioaccess node is not comprehensible by the source radio access node 103,for example because the source radio access node 103 and the previousradio access node may support different specification releases and/orfunctionality. By implementing backwards compatibility in protocols, theradio access nodes may still be able to cooperate for the functionalitysupported by both radio access nodes. Whenever the protocols evolve,extension fields may be introduced for newly added functionality.

Backwards compatibility may be provided by configuring radio accessnodes that do not support such newly added functionality and/or do notcomprehend the associated extension fields or parameters to ignore theextensions or parameters, as the case may be. Nodes that supporttransparent transfer or forwarding may be able to identify the end ofthe state information, for example based on the size of the container inwhich the state information is included, without having to comprehendthe details of the statue information (which is otherwise needed whenusing packed encoding rules (PER)).

In some cases, it may not seem beneficial or even desirable, tointroduce ‘transparent forwarding’ of state information from a previousradio access node to the source radio access node 103 when the stateinformation is not comprehensible by the source radio access node 103since such transparent forwarding would allow forwarding of stateinformation to nodes that do not comprehend the state information.

While connected to such nodes, the UE 102 cannot provide stateinformation reports and, hence, the forwarded state information might beoutdated when it reaches the next radio access node. In such cases, thetransfer of state information transparently may only serve to increaseoverall signalling in the radio access network 101, which is generallyundesirable.

However, in some cases, transparent forwarding may be desirable. Forexample, it may typically be more difficult to upgrade femto radioaccess nodes than it is to upgrade macro radio access nodes.Consequently, it is quite possible that a femto radio access node wouldconform to an earlier (older) specification release than a macro radioaccess node. If the UE 102 operates on a frequency in which femto radioaccess nodes are deployed, the UE 102 may regularly connect to a radioaccess node that uses an old release that may not support stateinformation reporting.

Since femto cells are relatively small, the stay by the UE 102 in suchcells may be rather short. Thus, it is quite possible that after passingthrough a femto cell, the UE 102 status is still valid. In such cases,it may be desirable to provide support for transparent forwarding of thestate information by nodes that support transparent transfer but thatmay not support state information reporting in relation to features forwhich state information reporting is added in later releases.

As explained above, is generally desirable that unnecessary stateinformation reporting by the UE 102 be minimised. As such, the UE 102 isconfigured to transmit a current value associated with a given stateinformation part to the target radio access node 104 in response todetecting at least one of one or more predetermined triggers thatindicate that the target radio access node 104 may not have received thecurrent value from the source radio access node 103. The UE 102 relieson the target radio access node 104 having received the current valuefrom the source radio access node 103 if said at least one of said oneor more predetermined triggers is not detected. Thus, in someembodiments, the at least one predetermined trigger acts as an indicatorthat the target radio access node 104 may not have received, is unlikelyto have received, or has not received, the current value from the sourceradio access node 103. In such cases, the UE 102 can report the currentvalue to the target radio access node 104 so that the target radioaccess node 104 has up-to-date state information relating to the UE.

In some embodiments, the one or more predetermined triggers includedetermining that the target radio access node 104 has not received thecurrent value from the source radio access node 103. In suchembodiments, the UE 102 reports the current value to the target radioaccess node 104 so that the target radio access node 104 has up-to-datestate information relating to the UE 102.

In some embodiments, the one or more predetermined triggers includedetermining that the current value has not been reported to the radioaccess network 101. In such embodiments, the UE 102 may determine thatthe target radio access node 104 has not received the current value,since the current value has not been reported. In response to detectingsuch a trigger, the UE 102 reports the current value to the target radioaccess node 104 so that the target radio access node 104 has up-to-datestate information relating to the UE 102.

In some embodiments, the one or more predetermined triggers includedetermining that the current value may have been reported to the sourceradio access node 103 too late for the source radio access node 103 tohave transmitted it to the target radio access node 104. It is possiblethat the value associated with the given state information part and/orother state information relating to the UE 102 changes after the sourceradio access node 103 has provided the latest state information it hasrelating to the UE 102 to the target radio access node 104. Thissituation is generally referred to herein as a “late change”.

In such a situation, the UE 102 may be configured to report the updatedstate information immediately following a cell change. Thus, in someembodiments, in the event that the state information has changed afterthe source radio access node 103 provided the state information relatingto the target radio access node 104 (a late change), the UE 102 provides(again) the updated state information to the target radio access node104, possibly immediately, following a handover or other change inconnection.

However, the UE 102 may not know when exactly the source radio accessnode 103 provided the latest state information it had relating to the UE102 to the target radio access node 104. Accordingly, various mechanismsare provided by means of which the UE 102 can detect whether a latechange occurred. Two such mechanisms are discussed below: a timer-basedscheme and a scheme in which version information is exchanged betweenthe UE 102 and the radio access network 101. Other suitable mechanismsmay, however, be used.

For UEs 102 in connected mode, the radio access network 101 typicallyinitiates a cell change in response to a measurement report from the UE102 indicating that the current serving cell is not optimal from a radioperspective. It is, however, also possible for the radio access network101 to initiate a cell change for other reasons, for example the cellload. In such cases, handover may not be preceded by a measurementreport. This is often referred to as a ‘blind handover’. In such cases,the UE 102 cannot use the measurement report message as a roughindication of the time at which the source radio access node 103 islikely to have initiated handover preparation and have provided thelatest state information it had relating to the UE 102 to the targetradio access node 104. As such, the UE 102 may employ a timer to detectthe occurrence of a late change.

In some embodiments, the one or more predetermined triggers includedetermining that the current value was reported to the source radioaccess node 103 within at least one predetermined time period prior toreceiving a message relating to the change in connection. In someembodiments, the one or more predetermined triggers include determiningthat the current value was reported to the source radio access node 103within at least one predetermined time period prior to detecting afailure in a connection to the source radio access node. Thus, in someembodiments, in the event that the state information has changed withina certain time period before the UE 102 receives the handover command ordetects a failure with respect to the source radio access node 103, theUE 102 provides the updated state information to the target radio accessnode 104, possibly immediately, following handover or re-establishmentas the case may be.

In some embodiments, the at least one predetermined time period includesa time period specified in a telecommunications standard, for example inone or more releases of 3GPP specification number TS 36.300. In someembodiments, the at least one predetermined time period includes a timeperiod configured by the radio access network 101. Thus, in someembodiments, the time period during which a change in state informationformation would trigger the UE 102 to provide an update may either byfixed (for example a value specified in the standard) or may beconfigured by the radio access network 101.

In some embodiments, the at least one predetermined time period includesa time period associated with a handover message. In some embodiments,the at least one predetermined time period includes a time periodassociated with a connection reestablishment procedure. Thus, in someembodiments, for handover and reestablishment, different time periods,during which a change in state information would trigger the UE 102 toprovide an update, may be used.

In some embodiments, the one or more predetermined triggers includereceiving, from the target radio access node 104, a message comprisingat least one predetermined indicator from which it can be determinedwhether or not the target radio access node 104 has received the currentvalue from the source radio access node 103. In such embodiments, the UE102 can use the at least one predetermined indicator to determinewhether or not the target radio access node 104 has received the currentvalue from the source radio access node 103.

Another mechanism for the detection of late changes of UE stateinformation upon handover or other changes in connection is for the UE102 to provide a version identifier when reporting the stateinformation. Thus, in some embodiments, the at least one predeterminedindicator comprises a version identifier indicating a version of atleast the given state information part.

In some such embodiments, the one or more predetermined triggers includedetermining that the version identifier received from the target radioaccess node 104 does not correspond with a current version of the givenstate information part. Thus, in some embodiments, the UE 102 may usethe version identifier received in the message from the target radioaccess node 104 to determine whether the target radio access node 104has outdated state information relating to the UE 102. If the versionidentifier received in the message does not correspond to the currentversion of the state information, the UE 102 provides the updated stateinformation following the change in connection.

Some embodiments comprise including a version identifier indicating aversion of the given state information part when reporting the valueassociated with the given state information part to the radio accessnetwork 101. Some embodiments comprise including a version identifierindicating a version of the given state information part when reportinga change in the value associated with the given state information partto the radio access network 101.

Some such embodiments comprise advancing the version identifierindicating the version of the given state information part upontransmitting the change in the value associated with the given stateinformation part to the radio access network 101. Some such embodimentscomprise advancing the version identifier indicating the version of thegiven state information part upon reporting the change in the valueassociated with the given state information part to the radio accessnetwork 101.

Thus, in some embodiments, whenever the UE 102 provides stateinformation, it includes a version identifier. In some cases, the UE 102steps the version identifier whenever it transfers state informationthat is different from state information that was previously transmittedto the radio access network 101. The UE 102 may consider the stateinformation to have been transferred successfully if one or moreappropriate acknowledgements is received at lower layers.

In certain cases, the UE 102 steps the version identifier whenever ittransmits state information that is different from state informationthat was previously transmitted, regardless of whether the transmittedstate information was known to be received successfully by the radioaccess network 101, since an acknowledgement might not be received eventhough the radio access network 101 had successfully received the stateinformation.

For state information parts whose associated values changes frequently,late changes are not unlikely. A separate version identifier may beapplied to such state information parts. In other cases in which latechanges are unlikely, it may be sufficient to use one, common versionidentifier to cover some or all state information parts collectively.Thus, in some embodiments, the version identifier is a common versionidentifier that indicates a version of both the given state informationpart and at least one additional state information part. Thus, in someembodiments, a single version identifier (referred to herein as a“common version identifier”) may be used to cover a plurality ofseparate state information parts.

Some such embodiments comprise including the common version identifierwhen reporting the value associated with the given state informationpart and/or the at least one additional state information part to theradio access network 101. Some such embodiments comprise including thecommon version identifier when reporting a change in the valueassociated with the given state information part and/or the at least oneadditional state information part to the radio access network 101.

Some such embodiments comprise advancing the common version identifierupon transmitting the change in the value associated with the givenstate information part and/or the at least one additional stateinformation part to the radio access network 101.

Thus, in some embodiments, when using a common version identifier, theUE 102 steps the version identifier whenever it transfers a stateinformation part that has a value that is different from the valueassociated with the state information part that was previouslytransmitted.

In some such embodiments, the one or more predetermined triggersinclude: determining that the common version identifier received fromthe target radio access node 104 does not correspond with a currentcommon version of the given state information part and the at least oneadditional state information part; and determining that the valuecurrently associated with the given state information part is differentfrom the value associated with a version of the given state informationpart as indicated by the received common version identifier.

Thus, in some embodiments, in the event that the common versionidentifier received in the message from the target radio access node 104does not correspond with the version of the state information that theUE 102 has, the UE 102 provides updated state information including atleast the values of the state information parts that changed compared tothose in relation to the version identifier received in the message fromthe target radio access node 104.

In some embodiments, the message received from the target radio accessnode 104 relates to handover. In other embodiments, the message receivedfrom the target radio access node 104 relates to a connectionre-establishment procedure. In some embodiments, the message receivedfrom the target radio access node relates to neither a handover commandnor a connection re-establishment procedure. For example, the messagemay be a dedicated message from the target radio access node or mayrelate to one or more procedures other than handover orre-establishment.

In some embodiments described above, a version identifier is used todetermine whether the last (successful) state information report inwhich the value associated with the given status element was reportedwas potentially too late for the source radio access node 103 to havetransmitted it to the target radio access node 104.

However, the network need not provide an indication that it received aprevious value associated with the given state information part fromanother radio access node, such as the source radio access node 103.This as this can be indicated implicitly, for example by the absence ofthe version identifier or by the inclusion of a specific versionidentifier value.

For example upon change a from a cell in which the UE 102 is notconfigured to report on the given state information part to a cell inwhich the UE 102 is configured to report on the given state informationpart, the UE 102 may (again) provide the updated value associated withthe given state information part in the event that the target radioaccess node 104 indicates in a message that it transmits to the UE 102that it does not have the updated value associated with the given stateinformation part by not providing any version identifier, by means of aspecial or predefined version identifier value or by means of a separateindication, for example by using a separate indication for each stateinformation part in the event that a common version identifier is used.

Thus, in some embodiments, the given state information part isassociable with a version identifier that indicates a version of thegiven state information part and the at least one predeterminedindicator includes a predetermined version identifier. In someembodiments, the given state information part is associable with aversion identifier that indicates a version of the given stateinformation part and the at least one predetermined indicator includesthe absence of a version identifier associated with the given stateinformation part.

In some embodiments, the one or more predetermined triggers includedetermining that the source radio access node 103, and/or or one moreradio access nodes to which the UE 102 was previously connected sincethe value currently associated with the given state information part wasreported to the radio access network 101, does not support forwarding ofstate information relating to the UE 102.

The indication that the target radio access node 104 does not havecurrent state information may be provided in at least two differentways. One way in which the target radio access node 104 may indicatethat it does not have the current state information is by indicatingthat it does not have any value associated with a particular stateinformation part, for example using dedicated signalling.

Another way in which it may be indicated that the target radio accessnode 104 does not have the current state information is for the radioaccess network 101 to indicate whether each cell or associated radioaccess node supports transparent transfer of state information relatingto the user, for example by using broadcast signalling. In the lattercase, the UE 102 assumes that target radio access node 104 does not havea current value associated with the given state information part if theUE 102 was connected to one or more cells that did not supporttransparent transfer of state information since it last provided anupdated value associated with the given state information part to theradio access network 101.

Thus, the target radio access node 104 may indicate whether or not ithas a value associated with the given state information part. The radioaccess network 101 may, also or alternatively, indicate for each cellwhether or not the cell supports transparent transfer of stateinformation relating to the UE 102. This may either be provided by usingbroadcast signalling, such as system information, or by using dedicatedsignalling as explained above.

In the event of using dedicated signalling, the UE 102 assumes that thetarget radio access node 104 does not have a value associated with thegiven state information part if the UE 102 was connected to one or morecells that did not support transparent transfer of status info since itlast provided a state information report for the one or more featuresassociated with the given state information part.

Some embodiments comprise transmitting the value currently associatedwith the given state information part to the target radio access node104 in response to said detecting at least one predetermined triggeronly if the given state information part is associated with one or morefeatures for which state information reporting is configured in thesecond cell 106.

One consideration is what state information the UE 102 should includewhen repeating the state information reporting due to a late change.Different radio access nodes may configure state information reportingfor different features, for example because the radio access nodes areprovided by different vendors and do not support the same set offeatures. For example, in the first cell 105, the UE 102 may beconfigured to perform state information reporting for features A and B,while in the second cell 106 the UE 102 may be configured to performstate information reporting for features B and C.

In embodiments described above, unnecessary repeating of stateinformation reporting may be reduced for the features that are sharedbetween the first cell 105 and the second cell 106, in this case featureB. Additionally, the UE 102 may provide a state information report forthe features that are newly configured by the second cell 106; thosethat are not shared with first cell 105 ? in this case feature C.Furthermore, the UE 102 need not repeat state information reporting dueto a late change in relation to a feature, such as feature A in theexample above, that is not configured in the second cell 106. Thus, insome embodiments, the UE 102 may be configured to repeat updated stateinformation following a handover or another change in connection only ifthe late change concerned one or more features that are configured inthe second cell 106 (irrespective of whether or not they are alsoconfigured in the first cell 105).

In some embodiments, the one or more predetermined triggers includedetermining that the given state information part is associated with oneor more features for which state information reporting is configured inthe second cell 106 and for which state information reporting is notconfigured in the first cell 105. As such, whenever the UE 102 movesfrom a cell associated with a radio access node that does support stateinformation reporting for a particular feature to a node supportingreporting of the particular feature, the UE 102 reports the currentvalue associated with the given state information part.

Thus, in some embodiments, following a change in connected mode from afirst cell 105 in which the UE 102 is not configured to report (changesto) a particular state information part to a second cell 106 in whichthe UE 102 is configured to report (changes to) the particular stateinformation part, the UE 102 initiates a state information reportregardless of whether or not the value associated with the particularstate information part has changed compared to what was included in apreviously sent state information report identifying a previous valueassociated with the particular state information part.

In some embodiments, the given state information part is associated withone or more features for which state information reporting is configuredin the second cell 106 and for which state information reporting is notconfigured in the first cell 105.

In other embodiments, the given state information part is associatedwith one or more features for which state information reporting isconfigured in both the first cell 105 and the second cell 106. Suchembodiments reduce unnecessary state information reporting by the UE 102following a cell change, for example handover or reestablishment, inconnected mode between cells in which the UE 102 is configured to reportchanges or updated associated with the given state information in bothcells.

State information reporting by the UE 102 may include several proceduralaspects, at least some of which may be handled in a common manner, whileother aspects may need to be handled separately in relation to some ofthe state information parts.

Some embodiments comprise transmitting an additional current valueassociated with a further given state information part to the targetradio access node in response to detecting at least one of one or morepredetermined triggers that indicate that the target radio access nodemay not have received the additional current value from the source radioaccess node and relying on the target radio access node having receivedthe additional current value from the source radio access node if saidat least one of said one or more predetermined triggers is not detected.

In some embodiments, at least the current value and the additionalcurrent value are included in a single message to the target radioaccess node. Thus, in some cases, a common message or procedure isintroduced for the common reporting of several different stateinformation parts. Common procedural aspects are specified at the levelof this common message.

Nevertheless, it may still be desirable to have a proceduralspecification for the state information parts included in the commonmessage. This may be achieved by treating the different stateinformation parts as if they were separate messages, so that the commonmessage would be considered as a list of individual messages.

FIG. 2 shows a method of processing state information relating to userequipment according to some embodiments.

At least some embodiments described above may result in modifications toprocedures and information specified in 3GPP TS 36.331, “EvolvedUniversal Terrestrial Radio Access (E-UTRA); Radio Resource Control(RRC); Protocol specification”. Some modifications may include:

-   -   using a common message (UEStateIndication) to report at least        the current value associated with the given state information        part, for example following detection of late changes during        handover;    -   extending the AS-Context field within the HandoverPreparation        message to include at least the current value, possibly as well        as a version identifier; and    -   extending the RRCConnectionReconfiguration message, which is        used to convey a handover command, to include the version        identifier.

In some embodiments, the otherconfig field, within anRRCConnectionReconfiguration message may be used to indicate timinginformation. In some embodiments, a UEStateInformation message may serveas a common state information message that includes an indication of(one or more) current version(s) of the state information. TheUEStateInformation message my include both one of more state informationvalues, for example indicating MBMS interest, as well as one or moreversion identifiers.

In some embodiments, a new field may be provided within theRRCConnectionReconfiguration message to indicate the version(s) of stateinformation that is available in the E-UTRAN upon handover. In someembodiments, the MeasurementReport message that the UE sends to theE-UTRAN may also be modified.

FIG. 3 shows a method of processing state information relating to userequipment in a communications system according to some embodiments. Inthese embodiments, a single, common version identifier is used to coverall of the state information parts making up the state information.

In this example, the state information relating to the user equipmentcomprises three different state information parts, denoted A, B and Cand associated with features A, B and C respectively.

Three cells are depicted in which state information reporting isconfigured for different features. State information reporting forfeatures A and B is configured in a first cell. State informationreporting is not configured at all in a second cell. However, the secondcell supports transparent forwarding of state information; in otherwords, although the second radio access node that controls the secondcell does not comprehend state information that it receives from thefirst radio access node that controls the first cell, it forwards thestate information to the third radio access node that controls the thirdcell. State information reporting for features B and C is configured ina third cell.

The UE 102 establishes an initial connection to the first radio accessnode, where it performs state information reporting for features A and Band includes a version identifier Vn=1 when reporting. At time T1, whilethe UE 102 is still in the first cell, the value of the stateinformation part associated with feature A changes. The UE 102 transmitsthe updated value of the state information part associated with featureA to the first radio access node and steps the version identifier toVn=2.

The UE 102 then moves, in connected mode, to the second cell. The firstradio access node transmits the latest state information it has relatingto the UE 102 to the second radio access node even though the secondradio access node does not comprehend the state information.

At time T2, while the UE 102 is in the second cell, the value of thestate information part associated with feature B changes. Since thereporting of changes associated with feature B is not configured in thesecond cell, the UE 102 does not report the changed value to the secondradio access node and does not step the version identifier associatedwith the state information.

The UE 102 then moves, in connected mode, from the second cell to thethird cell. The second radio access node transmits the latest stateinformation it has relating to the UE 102—which is the state informationit received from the first radio access node—to the third radio accessnode. In this case, the second radio access node transparently transfersthe state information to the third radio access node.

The UE receives a message from the third radio access node whichincludes the version identifier Vn=2. This corresponds to the version ofthe state information that was transparently forwarded by the secondradio access node.

The UE 102 determines that the third cell supports reporting of featuresB and C. The UE 102 does not transmit the current value associated withfeature A (which was changed at time T1) to the third radio access nodesince reporting of feature A is not configured in the third cell. The UE102 determines that it has not transmitted the updated value associatedwith feature B (which was changed at time T2) to the radio accessnetwork. The UE 102 also determines that it has not transmitted the(current) value associated with feature C to the radio access network,since reporting of feature C was not configured in either the first orsecond cell.

As such the UE 102 transmits, in a common message, the current valueassociated with feature B (which was updated at time T2) and the currentvalue associated with feature C at time T3 while the UE 102 is connectedto the third cell and updates the version identifier associated with thestate information to Vn=3.

FIG. 4 shows a method of processing state information relating to UE 102in a communications system according to some embodiments. In theseembodiments, a single, common version identifier is used to cover all ofthe state information parts making up the state information.

The method shown in FIG. 4 is similar to that shown in FIG. 3. However,in this example, reporting of feature A, in addition to features B andC, is configured in the third cell.

In particular, the UE 102 establishes an initial connection to the firstradio access node, where it performs state information reporting forfeatures A and B and includes a version identifier Vn=1 when reporting.At time T1, while the UE 102 is still in the first cell, the value ofthe state information part associated with feature A changes. The UE 102transmits the updated value of the state information part associatedwith feature A to the first radio access node and steps the versionidentifier to Vn=2. However, in this example, the UE 102 reports thechanges value associated with feature A just prior to the UE 102 moving,in connected mode, to the second cell.

The first radio access node transmits the latest state information ithas relating to the UE 102 to the second radio access node even thoughthe second radio access node does not comprehend the state information.In this example, the first radio access node did not receive the updatedstate information from the UE 102 in time for it to be transmitted tothe second radio access node. As such, the state information transmittedby the first radio access node to the second radio access node is theinitially reported state information associated with the versionidentifier Vn=1.

At time T2, while the UE 102 is in the second cell, the value of thestate information part associated with feature B changes. Since thereporting of changes associated with feature B is not configured in thesecond cell, the UE 102 does not report the changed value to the secondradio access node and does not step the version identifier associatedwith the state information.

The UE 102 then moves, in connected mode, from the second cell to thethird cell. The second radio access node transmits the latest stateinformation it has relating to the UE 102—which is the state informationit received from the first radio access node—to the third radio accessnode. In this case, the second radio access node transparently transfersthe state information to the third radio access node. In this example,the transparently transferred state information include the versionidentifier Vn=1.

The UE 102 receives a message from the third radio access node whichincludes the version identifier Vn=1. This corresponds to the version ofthe state information that was transparently forwarded by the secondradio access node.

The UE 102 determines that the third cell supports reporting of featuresA, B and C. The UE 102 determines that the third radio access node doesnot have the current value associated with feature A since the versionidentifier it received from the third radio access node (Vn=1) does notcorrespond with the current version of the state information (Vn=2). TheUE 102 determines that the value associated with feature A changedbetween the first and second version and determines that the currentvalue associated with feature A is to be transmitted to the third radioaccess node.

The UE 102 determines that it has not transmitted the updated valueassociated with feature B (which was changed at time T2) to the radioaccess network. The UE 102 also determines that it has not transmittedthe (current) value associated with feature C to the radio accessnetwork, since reporting of feature C was not configured in either thefirst or second cell.

As such the UE 102 transmits, in a common message, the current valueassociated with feature A (which was updated at time T1), feature B(which was updated at time T2) and the current value associated withfeature C at time T3 while the UE 102 is connected to the third cell andupdates the version identifier associated with the state information toVn=3.

FIG. 5 shows a method of processing state information relating to userequipment in a communications system according to some embodiments. Inthese embodiments, a single, common version identifier is used to coverall of the state information parts making up the state information.

In this example, the state information relating to the user equipmentcomprises three different state information parts, denoted A, B and Cand associated with features A, B and C respectively.

Four cells are depicted in which state information reporting isconfigured for different features. State information reporting forfeatures A and B is configured in a first cell. State informationreporting is not configured at all in a second cell. In this example,the second cell does not support transparent forwarding of stateinformation. State information reporting for features B and C isconfigured in a third cell. State information reporting for features Aand B is configured in a fourth cell.

The UE 102 establishes an initial connection to a first radio accessnode that controls the first cell, where it performs state informationreporting for features A and B and includes a version identifier Vn=1when reporting. At time T1, while the UE 102 is still in the first cell,the value of the state information part associated with feature Achanges. The UE 102 transmits the updated value of the state informationpart associated with feature A to the first radio access node and stepsthe version identifier to Vn=2.

The UE 102 then moves to the second cell. However, since the secondradio access node that controls the second cell does not supporttransparent forwarding of state information, the second radio accessnode does not receive state information from the first radio accessnode.

At time T2, while the UE 102 is in the second cell, the value of thestate information part associated with feature B changes. Since thereporting of changes associated with feature B is not configured in thesecond cell, the UE 102 does not report the changed value to the secondradio access node and does not step the version identifier associatedwith the state information.

The UE 102 then moves the second cell to the third cell. Since thesecond radio access node does not support transparent forwarding ofstate information, the third radio access node does not receive thestate information from the second radio access node.

The UE 102 receives a message from the third radio access node whichincludes a predetermined indicator from which the UE 102 can determinethat the third radio access node does not have current stateinformation. For example, the third radio access node may include noversion identifier or a special parameter in a message to the UE 102.

The UE 102 determines that the third cell supports reporting of featuresB and C. The UE 102 does not transmit the current value associated withfeature A (which was changed at time T1) to the third radio access nodesince reporting of feature A is not configured in the third cell. The UE102 determines that it has not transmitted the updated value associatedwith feature B (which was changed at time T2) to the radio accessnetwork. The UE 102 also determines that it has not transmitted the(current) value associated with feature C to the radio access network.As such the UE 102 transmits, in a common message, the current valueassociated with feature B (which was updated at time T2) and the currentvalue associated with feature C at time T3 while the UE 102 is connectedto the third cell and updates the version identifier associated with thestate information to Vn=3.

At time T3, while the UE 102 is in the third cell, the value of thestate information part associated with feature B changes. Since thereporting of changes associated with feature B is configured in thethird cell, the UE 102 reports the changed value to the third radioaccess node and step the version identifier associated with the stateinformation to Vn=4.

The UE 102 then moves, in connected mode, from the third cell to thefourth cell. The third radio access node transmits the latest stateinformation it has relating to the UE 102 to the fourth radio accessnode and includes the version identifier Vn=4.

The UE receives a message from the fourth radio access node whichincludes the version identifier Vn=4.

The UE 102 determines that the fourth cell supports reporting offeatures A and B.

However, the UE 102 remembers determining that the second cell did notsupport transparent transfer of state information and that the fourthradio access node will not have the current value associated withfeature A since reporting of feature A was not configured in the thirdcell. As such, the UE 102 determines that it will need to transmit thecurrent value associated with feature A to the fourth radio access node.

The UE 104 compares the version identifier it received from the fourthradio access node, Vn=4, to the current version identifier, Vn=4, anddetermines that the fourth radio access node has the current valueassociated with feature B. As such, the UE 104 determines that it neednot transmit the current value associated with feature B to the fourthradio access node. Accordingly, the UE 102 transmits the current valueassociated with feature A to the fourth radio access node and updatesthe version identifier associated with the state information to Vn=5.

In some embodiments described above, the target radio access node 104controlling the second cell 106 does not have up to date stateinformation as a result of a change in connection from the source radioaccess node 103 to the target radio access node 104. However, at leastsome of the procedures described above, in particular relating todetermining when the UE 102 should provide a new state informationreport, may also apply when the UE 102 moves from one cell to anothercell, even if both cells are controlled by the same radio access node.In such cases, the UE may be configured to determine whether there is aneed to provide a new state information report.

FIG. 6 is a block schematic representation of a communications system600 according to some embodiments. The communications system 600depicted in FIG. 6 includes some elements that are the same as, or aresimilar to, elements shown in FIG. 1. Such elements are given the samereference numerals as used above in relation to FIG. 1 but areincremented by five hundred.

The communication system 600 depicted in FIG. 6 includes a radio accessnetwork 601, which includes a radio access node 604. The radio accessnode 604 controls first and second cells 605, 606. UE 602 cancommunicate with the radio access node 604 via a radio interface 611.

Some embodiments provide a method of processing state informationrelating to user equipment in a communications system 600 comprising aradio access network 601. The communications system 600 comprises afirst cell 605 and a second cell 606. In some embodiments, the firstcell 605 and the second cell 606 are controlled by the same radio accessnode 604. The method comprises maintaining current state informationrelating to the user equipment 602.

The state information comprises at least one state information partassociated with one or more features for which state informationreporting may be configured in the first cell 605 and/or the second cell606. The at least one state information part is associable with aplurality of different values. The UE 602 is configured to detect aconnection change to the second cell. The UE is configured to transmit acurrent value associated with a given state information part to a radioaccess node 604 associated with the second cell 606 in response todetecting at least one of one or more predetermined triggers thatindicate that the radio access node 604 associated with the second cell606 may not have the current value. The UE 602 is configured to rely onthe radio access node 604 associated with the second cell 606 having thecurrent value if said at least one of said one or more predeterminedtriggers is not detected.

Some embodiments provide a method of processing state informationrelating to user equipment in a communications system 600 comprising aradio access network 601. The communications system 600 comprises atleast one cell 605, 606 that is controlled by the radio access node 604.The method comprises maintaining current state information relating tothe user equipment 602.

The state information comprises at least one state information partassociated with one or more features for which state informationreporting may be configured in the at least one cell 605, 606. The atleast one state information part is associable with a plurality ofdifferent values.

The UE 602 is configured to detect a connection change in relation tothe at least one cell 605, 606. The UE is configured to transmit acurrent value associated with a given state information part to a radioaccess node 604 associated with the at least one cell 605, 606 inresponse to detecting at least one of one or more predetermined triggersthat indicate that the radio access node 604 associated with the atleast one cell 605, 606 may not have the current value.

The UE 602 is configured to rely on the radio access node 604 associatedwith the second cell 606 having the current value if said at least oneof said one or more predetermined triggers is not detected. In suchembodiments, the UE 602 may perform such processing even where there isno change of cell, for example in the case of reestablishing aconnection to the radio access node 604 following detecting of a failuretherewith.

At least some embodiments described above reduce the need for the UE102, 602 to repeat state information reporting after every cell changein connected mode, for example as part of a handover or connectionre-establishment procedure. In some embodiments, a source RAN node, suchas a source eNb, forwards UE state information to a target RAN node,such as a target eNb.

In some embodiments, following a cell change in connected mode from acell in which the reporting of UE state information is not configured toa cell in which the reporting of UE state information is configured, theUE 102, 106 always provides updated state information. In someembodiments, following a cell change in connected mode between cells inwhich the reporting of UE state information is configured, the UE 102provides updated state information if: at least part of the stateinformation changed shortly before the cell change and/or if a ‘version’received from the target radio access node 104 indicates that the targetradio access node 104 does not have up-to-date UE state information.

In some such embodiments, a version can be exchanged on the basis ofindividual state information parts or a common version can be used tocover a plurality of state information parts. In some embodiments, acommon message or procedure may be used to specify the elements(information as well as procedural aspects) that are common for allstate information parts only once. At least some embodiments providemechanisms to limit repeated state information reporting by the UE 102,602 after every cell change in connected mode.

Some embodiments seek to minimise the repetition, by transferring stateinformation from a source node to a target node, complemented with theUE 102, 062 providing one or more state information reports in the eventthat the state information may have changed after the source nodetransferred the state information to the target node.

The above embodiments are to be understood as illustrative examples ofthe invention. Further embodiments of the invention are envisaged.

In the above embodiments, the version identifier may be a versionnumber. Other types of version identifier such as letters or othersymbols or parameters are envisaged. Furthermore, although embodimentsabove refer to a ‘value’ associated with a state information part, itwill be appreciated that the value need not be numeric and may dependupon possible states of one or more features with which the stateinformation part may be configured.

It is to be understood that any feature described in relation to any oneembodiment may be used alone, or in combination with other featuresdescribed, and may also be used in combination with one or more featuresof any other of the embodiments, or any combination of any other of theembodiments. Furthermore, equivalents and modifications not describedabove may also be employed without departing from the scope of theinvention, which is defined in the accompanying claims.

1. A method of processing state information relating to user equipmentin a radio access network of a communication system, the methodcomprising: maintaining, by a source radio access node, current stateinformation relating to the user equipment, the state informationcomprising at least one state information part associated with one ormore features for which state information reporting may be configured ina cell, the at least one state information part being associable with aplurality of different values, wherein the source radio access node isassociated with one or more cells; performing, by the source radioaccess node, on the basis of a change of connection of the userequipment from a first cell to a second cell, at least one of:transmitting a current value associated with a given state informationpart to a target radio access node in response to detecting at least oneof one or more predetermined triggers that indicate that the targetradio access node may not have received the current value from thesource radio access node, or relying on the target radio access nodehaving received the current value from the source radio access node ifat least the one of the one or more predetermined triggers is notdetected; and receiving, by the target radio access node, the stateinformation from the source radio access node, wherein the target radioaccess node is associated with one or more cells.
 2. The methodaccording to claim 1, wherein the one or more predetermined triggers areused to determine that the target radio access node has not received thecurrent value from the source radio access node.
 3. The method accordingto claim 1, wherein the one or more predetermined triggers are used todetermine that the current value has not been reported to the radioaccess network.
 4. The method according to claim 1, wherein the one ormore predetermined triggers are used to determine that the current valuemay have been reported to the source radio access node too late for thesource radio access node to have transmitted it to the target radioaccess node.
 5. The method according to claim 1, wherein the one or morepredetermined triggers are used to determine that the current value wasreported to the source radio access node within at least onepredetermined time period prior to receiving a message relating to thechange in connection.
 6. The method according to claim 5, wherein the atleast one predetermined time period includes a time period associatedwith a handover command.
 7. The method according to claim 5, wherein themessage comprises a handover command.
 8. The method according to claim1, wherein the one or more predetermined triggers are used to determinethat the current value was reported to the source radio access nodewithin at least one predetermined time period prior to detecting afailure in a connection to the source radio access node.
 9. The methodaccording to claim 5, wherein the at least one predetermined time periodincludes a time period associated with a re-establishment procedure. 10.The method according to claim 5, wherein the at least one predeterminedtime period includes a time period specified in a telecommunicationsstandard.
 11. The method according to claim 5, wherein the at least onepredetermined time period includes a time period configured by the radioaccess network.
 12. The method according to claim 1, wherein the one ormore predetermined triggers are used to receive, from the target radioaccess node, a message comprising at least one predetermined indicatorfrom which it can be determined whether or not the target radio accessnode has received the current value from the source radio access node.13. The method according to claim 12, wherein the at least onepredetermined indicator comprises a version identifier indicating aversion of the given state information part.
 14. The method according toclaim 13, wherein the one or more predetermined triggers are used todetermine that the version identifier received from the target radioaccess node does not correspond with a current version of the givenstate information part.
 15. The method according to claim 1, furthercomprising: including a version identifier indicating a version of thegiven state information part when reporting the value associated withthe given state information part to the radio access network.
 16. Aradio access network of a communication system for processing stateinformation relating to user equipment, the radio access networkcomprising: a target radio access node configured to receive stateinformation from a source radio access node and that is associated withone or more cells; and the source radio access node configured tomaintain current state information that relates to the user equipmentand that is associated with one or more cells, wherein the stateinformation includes at least one state information part associated withone or more features to configure state information reporting in a cell,and wherein the at least one state information part is associated with aplurality of different values, and the source radio access node isconfigured to perform, on the basis of a change of connection of theuser equipment from a first cell to a second cell, at least one of:transmitting a current value associated with a given state informationpart to the target radio access node in response to detecting at leastone of one or more predetermined triggers that indicate that the targetradio access node may not have received the current value from thesource radio access node, or relying on the target radio access nodehaving received the current value from the source radio access node ifat least the one of the one or more predetermined triggers is notdetected.
 17. The radio access network according to claim 16, whereinthe one or more predetermined triggers are used to determine that thetarget radio access node has not received the current value from thesource radio access node.
 18. The radio access network according toclaim 16, wherein the one or more predetermined triggers are used todetermine that the current value has not been reported to the radioaccess network.
 19. The radio access network according to claim 16,wherein the one or more predetermined triggers are used to determinethat the current value may have been reported to the source radio accessnode too late for the source radio access node to have transmitted it tothe target radio access node.
 20. The radio access network according toclaim 16, wherein the one or more predetermined triggers are used todetermine that the current value was reported to the source radio accessnode within at least one predetermined time period prior to receiving amessage relating to the change in connection.